PSXI-6 - The effects cattle breed (Holstein vs Angus × Holstein) on growth performance, energetic efficiency, and carcass characteristics of calf-fed steers

Abstract: Objective of the current study was to evaluate the effects of cattle breed (Holstein vs Angus × Holstein) on growth performance, energetic efficiency, and carcass characteristics of calf-fed steers. Eighty Holstein (HOL), initial body weight (IBW) of 128.7 ± 3 kg, and 80 Angus × Holstein cross (CROS) with IBW of 127.1 ± 3 kg, were blocked by IBW and randomly assigned to 40 pens (4 steers/pen; 20 pens per breed). All steers were fed a similar steam-flaked corn-based diet (63.5% steam-flaked corn, 12.0% hay, 17.5% of dry distillers grains with solubles, 4.0% cane molasses, and 3.0% vitamin/mineral supplement). All cattle were slaughtered after 328 days of feed. There was no effect (P ≥ 0.13) of cattle breed on final body weight (615 ± 22 kg) and overall average daily gain (1.48 ± 0.07 kg/day). However, calf-fed HOL steers had greater (P = 0.04) overall dry matter intake compared to calf-fed CROS steers (8.06 vs. 7.79 ± 0.39 kg/day; respectively). Therefore, calf fed CROS steers had greater (P ≤ 0.01) grain to feed ratio compared to calf-fed HOL steers (0.192 vs. 0.182 ± 0.005; respectively). Moreover, calf-fed CROS steers had greater (P < 0.01) utilization of dietary net energy for maintenance (2.29 vs. 2.29 ± 0.06 Mcal/kg; respectively) and gain (1.51 vs 1.61 ± 0.06 Mcal/kg; respectively) compared to calf-fed HOL steers. Calf-fed CROS steers had greater (P ≤ 0.02) hot carcass weight (HCW; 386.3 vs. 375.2 ± 14.7 kg; respectively), dressing percentage (DP; 62.3 vs. 61.4 ± 1.05%; respectively), longissimus muscle area (LMA; 86.9 vs. 79.1 ± 4.83 cm²; respectively), backfat thickness (0.89 vs. 0.55 ± 0.12; respectively), and marbling score (538 vs. 449 ± 48; respectively). However, there were no effect (P = 0.26) of cattle breed on calculated USDA yield grade (2.94 ± 0.24). Moreover, there were no effect (P = 0.39) of cattle breed on incidence of liver abscesses. Therefore, cross breeding calf-fed Angus × Holstein increased HCW, DP, LMA, and marbling compared to purebred calf-fed Holstein steers. Moreover, regardless, of cattle breed, calf-fed steers in the current study had only 3.75% of liver with abscess.